Question: $28.2 \times 4.42 = $
Solution: ${2}$ ${8}$ ${2}$ ${4}$ ${4}$ ${2}$ ${\times\vphantom{0}}$ ${.}$ ${.}$ ${0.2}\times {0.02}= {0.004}$ ${4}$ ${8}\times {0.02}= {0.16}$ ${6}$ ${20}\times {0.02}+C{0.1}= {0.5}$ ${5}$ ${0.2}\times {0.4}= {0.08}$ ${8}$ ${0}$ ${8}\times {0.4}= {3.2}$ ${2}$ ${20}\times {0.4}+C{3}= {11}$ ${1}$ ${1}$ ${0.2}\times {4}= {0.8}$ ${8}$ ${0}$ ${0}$ ${8}\times {4}= {32}$ ${2}$ ${20}\times {4}+C{30}= {110}$ ${1}$ ${1}$ ${+\vphantom{0}}$ ${1}$ ${2}$ ${4}$ ${6}$ ${4}$ ${4}$ ${+\vphantom{0}}$ ${1}$ ${2}$ ${4}$ ${6}$ ${4}$ ${4}$ ${.}$ The top number has $1$ digit to the right of the decimal. The bottom number has $2$ digits to the right of the decimal. The product has $1+2=3$ digits to the right of the decimal. $28.2 \times 4.42 = 124.644$